Wells are generally drilled into a land surface or ocean bed to recover natural deposits of oil and gas, as well as other natural resources that are trapped in geological formations in the Earth's crust. Wellbores may be drilled along a trajectory to reach one or more subterranean rock formations containing such natural resources.
Coiled tubing technology may be utilized to reach the oil and gas deposits and to perform various wellbore intervention operations. The ability of coiled tubing to pass through completion tubulars and to utilize a wide array of tools and technologies in conjunction with the coiled tubing make coiled tubing a versatile technology. A typical coiled tubing apparatus includes surface pumping facilities, a coiled tubing string mounted on a reel, a method to convey the coiled tubing into and out of the wellbore (such as an injector head or the like), and surface control apparatus at a wellhead. Coiled tubing may be utilized for performing well treatment and/or well intervention operations in existing wellbores, such as, but not limited to, hydraulic fracturing, matrix acidizing, patching, milling, drilling, perforating, and the like.
In working with deeper and more complex wellbores, it becomes more likely that downhole tools, tool strings, bottom hole assemblies, and/or other downhole apparatus may include numerous testing, measurement, navigation, communication, and other downhole tools, resulting in increasingly longer tool strings. The length of downhole tools is often dependent on what function they perform, where additional functions typically imply additional length. As more and more sophisticated functions are performed downhole, tools have grown in length to the point where deploying them into a wellbore has become a significant challenge in face of maintaining well control.
In coiled tubing operations, downhole tools may be deployed into a wellbore via an injector head. To perform such operations, an assembled tool string may be pulled into a riser and positioned over the wellbore. The riser may then be attached to a blowout preventer (BOP) and utilized to seal off the wellbore while the tool string to be deployed into the wellbore. Using such method limits the overall length of the assembled tool string, as the length of the riser is limited by the height of a structure supporting the riser on top of the BOP.